Obviously, topic maps can carry information which is tree structured. A family pedigree is a typical example of it; associations having a particular type, particular roles and you can derive a tree structure from that.

This is exactly what this operator does: it takes one topic map basis and primed with a starting node, an association type and two roles a tree will be returned to the caller.

This function will analyze the topic map and will detect all maplets of the given type (direct and indirect ones) having the specified roles. Starting from the start topic it will so find other topics playing the brole. Those will be used as a next starting point, and so forth.

To avoid the tree to become too big, you can impose an optional limit. Loops are detected.

This function is a specialization of tree, in that it looks at a particular association type (is-subclass-of) and the appropriate roles (superclass, subclass). Obviously the result is a tree holding all subtypes.

The only optional parameter is a toplet lid; that becomes the starting point of the tree. If that parameter is missing, thing is assumed.